/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.dubbo.config.spring;

import org.apache.dubbo.common.URL;
import org.apache.dubbo.common.logger.Logger;
import org.apache.dubbo.common.logger.LoggerFactory;
import org.apache.dubbo.common.utils.CollectionUtils;
import org.apache.dubbo.common.utils.StringUtils;
import org.apache.dubbo.registry.NotifyListener;
import org.apache.dubbo.registry.RegistryService;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.CopyOnWriteArrayList;

/**
 * AbstractRegistryService
 */
public abstract class AbstractRegistryService implements RegistryService {

  // logger
  protected final Logger logger = LoggerFactory.getLogger(getClass());

  // registered services
  // Map<serviceName, Map<url, queryString>>
  private final ConcurrentMap<String, List<URL>> registered = new ConcurrentHashMap<String, List<URL>>();

  // subscribed services
  // Map<serviceName, queryString>
  private final ConcurrentMap<String, Map<String, String>> subscribed = new ConcurrentHashMap<String, Map<String, String>>();

  // notified services
  // Map<serviceName, Map<url, queryString>>
  private final ConcurrentMap<String, List<URL>> notified = new ConcurrentHashMap<String, List<URL>>();

  // notification listeners for the subscribed services
  // Map<serviceName, List<notificationListener>>
  private final ConcurrentMap<String, List<NotifyListener>> notifyListeners = new ConcurrentHashMap<String, List<NotifyListener>>();

  @Override
  public void register(URL url) {
    if (logger.isInfoEnabled()) {
      logger.info("Register service: " + url.getServiceKey() + ",url:" + url);
    }
    register(url.getServiceKey(), url);
  }

  @Override
  public void unregister(URL url) {
    if (logger.isInfoEnabled()) {
      logger.info("Unregister service: " + url.getServiceKey() + ",url:" + url);
    }
    unregister(url.getServiceKey(), url);
  }

  @Override
  public void subscribe(URL url, NotifyListener listener) {
    if (logger.isInfoEnabled()) {
      logger.info("Subscribe service: " + url.getServiceKey() + ",url:" + url);
    }
    subscribe(url.getServiceKey(), url, listener);
  }

  @Override
  public void unsubscribe(URL url, NotifyListener listener) {
    if (logger.isInfoEnabled()) {
      logger.info("Unsubscribe service: " + url.getServiceKey() + ",url:" + url);
    }
    unsubscribe(url.getServiceKey(), url, listener);
  }

  @Override
  public List<URL> lookup(URL url) {
    return getRegistered(url.getServiceKey());
  }

  public void register(String service, URL url) {
    if (service == null) {
      throw new IllegalArgumentException("service == null");
    }
    if (url == null) {
      throw new IllegalArgumentException("url == null");
    }
    List<URL> urls = registered.get(service);
    if (urls == null) {
      registered.putIfAbsent(service, new CopyOnWriteArrayList<URL>());
      urls = registered.get(service);
    }
    if (!urls.contains(url)) {
      urls.add(url);
    }
  }

  public void unregister(String service, URL url) {
    if (service == null) {
      throw new IllegalArgumentException("service == null");
    }
    if (url == null) {
      throw new IllegalArgumentException("url == null");
    }
    List<URL> urls = registered.get(service);
    if (urls != null) {
      URL deleteURL = null;
      for (URL u : urls) {
        if (u.toIdentityString().equals(url.toIdentityString())) {
          deleteURL = u;
          break;
        }
      }
      if (deleteURL != null) {
        urls.remove(deleteURL);
      }
    }
  }

  public void subscribe(String service, URL url, NotifyListener listener) {
    if (service == null) {
      throw new IllegalArgumentException("service == null");
    }
    if (url == null) {
      throw new IllegalArgumentException("parameters == null");
    }
    if (listener == null) {
      throw new IllegalArgumentException("listener == null");
    }
    subscribed.put(service, url.getParameters());
    addListener(service, listener);
  }

  public void unsubscribe(String service, URL url, NotifyListener listener) {
    if (service == null) {
      throw new IllegalArgumentException("service == null");
    }
    if (url == null) {
      throw new IllegalArgumentException("parameters == null");
    }
    if (listener == null) {
      throw new IllegalArgumentException("listener == null");
    }
    subscribed.remove(service);
    removeListener(service, listener);
  }

  private void addListener(final String service, final NotifyListener listener) {
    if (listener == null) {
      return;
    }
    List<NotifyListener> listeners = notifyListeners.get(service);
    if (listeners == null) {
      notifyListeners.putIfAbsent(service, new CopyOnWriteArrayList<NotifyListener>());
      listeners = notifyListeners.get(service);
    }
    if (listeners != null && !listeners.contains(listener)) {
      listeners.add(listener);
    }
  }

  private void removeListener(final String service, final NotifyListener listener) {
    if (listener == null) {
      return;
    }
    List<NotifyListener> listeners = notifyListeners.get(service);
    if (listeners != null) {
      listeners.remove(listener);
    }
  }

  private void doNotify(String service, List<URL> urls) {
    notified.put(service, urls);
    List<NotifyListener> listeners = notifyListeners.get(service);
    if (listeners != null) {
      for (NotifyListener listener : listeners) {
        try {
          notify(service, urls, listener);
        } catch (Throwable t) {
          logger.error("Failed to notify registry event, service: " + service + ", urls: " + urls
              + ", cause: " + t.getMessage(), t);
        }
      }
    }
  }

  protected void notify(String service, List<URL> urls, NotifyListener listener) {
    listener.notify(urls);
  }

  protected final void forbid(String service) {
    doNotify(service, new ArrayList<URL>(0));
  }

  protected final void notify(String service, List<URL> urls) {
    if (StringUtils.isEmpty(service)
        || CollectionUtils.isEmpty(urls)) {
      return;
    }
    doNotify(service, urls);
  }

  public Map<String, List<URL>> getRegistered() {
    return Collections.unmodifiableMap(registered);
  }

  public List<URL> getRegistered(String service) {
    return Collections.unmodifiableList(registered.get(service));
  }

  public Map<String, Map<String, String>> getSubscribed() {
    return Collections.unmodifiableMap(subscribed);
  }

  public Map<String, String> getSubscribed(String service) {
    return subscribed.get(service);
  }

  public Map<String, List<URL>> getNotified() {
    return Collections.unmodifiableMap(notified);
  }

  public List<URL> getNotified(String service) {
    return Collections.unmodifiableList(notified.get(service));
  }

  public Map<String, List<NotifyListener>> getListeners() {
    return Collections.unmodifiableMap(notifyListeners);
  }

}
